Position finding



Sept. 10, 1940. J. NEUFELD POSITION FINDING Filed June 12, 1937 2Sheets-Sheet l nwo ' lNvEN'roR owo: (YV/MA t. l0, 1940. I J. NEUFELDM4342 POSITION FINDING Filed June 12, 1937 2 Sheets-Sheet 2 SEASynchronous I Mo/or 29 28 #michi/fers l, f2 UUUUUUUUUUUO Fig. 3

laoa |24 Fig. 4 "2gl nod no4 INPUT INPUT TERM |NALs TERMINALS INVENTORmp, WOL

Patented Sept. 10, 1940 STATES smear orgies 14 Cliams.

My invention relates to a radio positioning method and mechanism.

An object of my invention is to provide a method for detecting visuallythe position of moving bodies such as ships or airplanes located in agiven geographical region.

A further object of my invention is to provide means whereby a givencoast line can be satisfactorily surveyed and protected during the time.

of war, by giving a continuous and visual indication of all the enemyships navigating near the shore.

A further object of my invention is to provide means for a simultaneous,continuous, and visual indication of all enemy airplanes ying over agiven territory.

A still further object of my invention is to produce a permanent recordof the .course of ships and airplanes located in a given geographicalregion. Thus a plane forced down in wild country or at sea may bequickly found. .An aviator approaching a mountain range may be madeaware of the fact and may choose his altitude accordingly even thoughthe mountains can not be seen, or a ship navigating by dead reckoningmay be constantly informed of its true position and may be safely guidedto its harbor.

In one of the embodiments of my invention I am accomplishing theseobjects by providing an apparatus by means of which any radio signalssent out by ships or airplanes may be picked up by two directionalreceiving stations, each receiving station having apparatusautomatically operable in response to incoming radio signals to indicatethe direction from which said signals are received, together withapparatus for combining said indications at a central point to form anindication of the exact position of all the sources of the said signals.

'Ihe novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My invention,itself, however, both as to its organization and method of operation,together with further ob- 45- jects and advantages thereof, will bebetter understood by reference to the following description taken inconnection with the accompanying drawings in which:

Figure 1 represents one embodiment of my invention.

Figure 2 represents another embodiment of my invention.

Figure 3 represents a photographic record obtained by means of thearrangement shown in Figure 2.

Figure 4 represents an electronic divider which constitutes an elementof the arrangement of Figure 1 and Figure 2.

Referring now more particularly to Figure 1 the symbols S1, Sz, Sndesignate enemy ships located near the coast MPN; A and B designate tworadio receiving stations having their aerial systems Ill and II spacedapart to ensure satisfaction of thev trigonometric conditions for goodposition fixing; C designates a low frequency gen- 10 erator'energizingsynchronous motors I2 and I3, the said motors being located at thestations A and B respectively. The motors I2 and I3 are on thev sameshaft I4 and I5 with tuning condensers I6, I1 and I8, I9 respectively,the said 15 tuning condensers being in continuous rotation so as tocover periodically in succession a certain predetermined tuningfrequency range of the aerials I0 and II.. The radio receiving stationsA and B are adapted to transmit automatically 20 and continuously thebearings of the ships S1, S2, Sn to a station D. The station D containstwo cathode ray oscillographs 20 and 2| in which the cathode ray beamsindicate on screens, spots representing positions of the vessels 25 S1,S2, Sn.Y v Y In such a manner, an observer in charge of the coastaldefense and located at the station D is constantly aware of the numberand exact position of the enemy ships approaching the sea 80 shore.

In the operation of the device it is assumed that the ships S1, S2, Snare provided with radio-transmitting stations transmitting signals atfrequencies f1, f2, fn respectively.

The arrow N shown in the figure indicates the direction of the truenorth; a1, a2, an are the bearings east of the true north of the shipsS1, S2, Sn resp. as taken by the station A, and ,31, e2, n, are thebearings west of the true 40 north of the ships S1, S2, Sn resp. astaken by the station B. The condensers I6 and I1 and the condensers I8and I9 are in a continuous rotation and enable the tuning range ofaerials I0 and II re- 4:5A

spectively to cover a predetermined frequency band Within a relativelyshort time interval. The said tuning conditions repeat themselvesperiodically in succession in such a manner that the aerials I0 and IIare repeatedly tuned at de ter- 50 mined instants to the frequencies f1,f2, fn of signals transmitted from the ships S1, S2, Sn respectively.

Thus the stations A and B are repeatedly and successively exposed tosignals from the ships hereafter the station A is made to produceautomatically the bearings ai, a2, an from the respective signalsreceived from the ships Si, S2, Sn. In the same manner the station B ismade to produce automatically the bearings 131, [32, n fromtheyrespective signals received from the ships. These bearings aretransmitted simultaneously with their respective frequencies f1, f2, fnfrom the stations A and B to the station D. I

Thus the station A is made to transmit to the station D continually andin a very rapid succession electrical signals representing the valuesai, f in the following cyclic order ahh; aafz; orafa; an, fn; a1, f1;az,f2;

In a similar manner the station B is made to transmit automatically tothe station D the signals The cathode ray tubes 20 and 2| in theobserving station D are of a standard construction, the tube 20 beingprovided with two pairs of deflecting electrodes 22 and 23 respectively,and the tube 2| being provided with two pairs of deflecting electrodes24 and 25 respectively.

'I'he signals a1, a2, an transmitted by the station A, are translatedinto electrical voltages which are applied successively across theelectrodes 22 of the cathode ray tube 20. Also, the voltagesrepresenting the values fr, fz, fn are applied successively across theelectrodes 23 and in such a manner that the voltage a1 coincides exactlyin time withthe voltage f1, the voltage a2 coincides with f2, etc.

It is well known to those skilled in the art that the electron beam in acathode r'ay tube produces on the screen a luminous spot, the positionof which is determined by the voltages a and f applied to the deflectingelectrodes 22 and 23 respectively.

Thus at the instant at which these voltages have the values a1, f1,resp., the luminous spot Will be deected horizontally by the value frand deflected vertically by the value a1.

It is therefore apparent that in the present arrangement the luminousspot will occupy the positions determined by ai, f1; a2, f2; an, fn; a1,f1;

in a very rapid and cyclic succession. By employing on the screen of thecathode ray oscillograph a uorescent material possessing an appreciableperiod of after-glow, the existence of the spots corresponding to theabove positions can be made apparently or in reality simultaneous. Thusthe presence and location of ships S1, Se, 'Sn is indicated visually onthe screen of the cathode ray tube 20 by points the abscissas of whichare f1, f2, ,fn and the ordinates a1, a2, am.

In a similar manner the signals S1, S2, Sn. By means which shall beexplained parent that a permanent record of the locations and paths ofthe ships may be provided by continuously projecting the indications ofthe cathode ray tubes 20 and 2| on a photographic plate or film.

Now various elements entering in the arrangement of Figure 1 will beexplained more in detail.

The aerial I consists of two directional antennae consisting of loops26, 21 respectively, and having their planes intersecting each other.The loops 26, 21 may be symmetrical and adjusted to produce the Wellknown iigure-in-eight pattern, or they may be asymmetrical andcharacterized by a vertical effect (by asymmetrical ground or otherwise)and adjusted to produce -cardioid patterns. The tuning condensers I6 andof the antennae 2B and 2 are set in a continual rotatory motion on acommon shaft I4 being driven by the synchronous motor |2. The twoantennae are inductively coupled to amplifiers 28, 29 respectively, thesaid ampliers having a constant and equal input output relationship overa Wide range of input frequencies. The ampliers 28, 29 are connected tothe respective transmission lines 30, 3|. These transmission lines serveas a link connecting the radio receiving station A with the observingstation D. At the observing station D the lines 30, 3| are connectedthrough the amplifiers 32, 33 to an electronic dividing arrangement 34.'I'he electronic dividing arrangement consists of a mechanism adapted toproduce an electrical effect which represents the quotient of two otherelectrical effects. In this particular case the voltage appearing acrossthe output terminals of the electronic divider 34 represents the voltagereceived from the amplifier 32 divided by the voltage received from theamplifier 33.

'Ihe output voltage of the electronic divider 34 is amplified in 35 andapplied across the deflecting electrodes 22 of the cathode ray tube 20.

The structural details and the operation of the electronic dividingarrangement shall be explained hereafter in connection with Figure 4.

In a similar manner the radio receiving station B is provided with twoloop antennae 36 and 31, the tuning of which is effected by means ofvariable condensers |8 and I9 the said condensers being rotated by theshaftJ of the synchronous motor |3. The output of the antennae 36 and 31is amplified in 38, 39 and subsequently transmitted through the lines 4Uand 4| to the observing station D. At the observing station the lines40, 4| are connected through the amplifiers 42, 43 to an electronicdividing arrangement 44 similar to the one designated by 34. 'I'heoutput voltage of the electronic dividing arrangement is amplified in 45and applied across the electrodes 24 of the cathode ray tube 2|.

Referring now again to the station A, a potentiometric arrangement 46 isprovided, which consists of a battery 41k delivering current through theresistor 48 and of an electrically conductive arm 50 mounted on therotating shaft |4. The point 49 of the arm 50 is electrically connectedthrough a portion of the shaft |4 and the brush 5| to one of thetransmission lines 52. On ,the other hand the point 53 of the arm 50during the rotation of the shaft slides continually on the resistor 48and is always electrically connected to the other transmission line 52through a, portion of the resistor 48 between the points 53 and 54. Itis apparent that the voltage across the lines 52 is equalto the voltagedrop across the portion of the resistor 48 between the points 53 75 and54. This voltage drop depends upon the instantaneous position of the arm50. On the other hand, it is known that the instantaneous position ofthe arm 50 determines the value of the tuning condensers I6, I1 andconsequently the frequency f to which the aerial Ill is tuned at thegiven instant. In such a manner the potentiometric arrangement 46 iscapable of delivering a voltage across the lines 52, the said voltagedetermining at any instant the corresponding frequency to which theaerial is tuned. This frequency determining voltage is subsequentlytransmitted across the lines 52 to the station D, wherein it isamplified in the amplier 55 and applied across the deecting electrodes23 of the cathode ray tube 20.

In a similar manner in the station B a potentiometric arrangement 56 isprovided which is adapted to deliver a voltage across the lines 62, thesaid voltage determining at any instant the corresponding frequency towhich the aerial Il is tuned. This frequency determining voltage issubsequently transmitted across the lines 62 to the station D wherein itis amplified in the amplier 65 and applied across the deiiectingelectrodes 25 of the cathode ray tube 2|.

Consider now an extremely short instant at which the aerial I is tunedto the frequency f1 of the signal sent by the ship S1. Let at thisinstant the ship be located on a line bisecting the planes of antennae2B and 21. It Will be apparent that the relative positions of S1 withrespect to both antennas are similar one to another and consequently theamount of energy received from the transmitter of the ship S1 will bethe same for antenna 26 as for antenna 21. Then the amplifiers 28 and 29respectively connected to the antennas 26 and 21 will consequentlydeliver equal voltages to the transmission lines 30 and 3| respectively.These voltages will be amplified again at 32, 33, applied to theelectronic divider 34 and will cause the electronic divider to produceacross its output terminals the voltage corresponding to the ratio one.The voltage derived from the electronic divider 34 will be subsequentlyamplified in 35 and applied across the deflecting electrodes 22 of thecathode ray tube. Thus the luminous spot on the screen of the tube willbe deiiected by a determined amount and this deflection will bemaintained as long as the vessel will be positioned on the referred linemaking an angle a1 with the direction of the north.

If however the vessel changes its angular relationship there is anincrease in responsiveness in one of the antennas of the aerial Ill anda corresponding decrease in the other antenna. In that connection it isimportant to note that the ratio of responsiveness of the two antennasremains constant for any given value of a1 irrespective from the signalstrength and distance from the vessel to the station. Consequently thevoltage applied across the electrodes 22 of the tube 2Il whichrepresents the value of the said ratio and determines the verticaldeflection of the luminous spot will represent at the same time thevalue a1 corresponding to the angular position of the vessel.

On the other hand, at the instant under consideration the rotating arm5U mounted on the shaft I4 will occupy a certain instantaneous position.Then, across the lines 52 there appears a voltage, the magnitude ofwhich represents the instantaneous position of the shaft I4 andconsequently represents also the frequency f1 to \which the aerial lIListuned at the instant under consideration. It is therefore apparent thatthe voltage applied to the electrodes 23 at the particular instant underconsideration represents the frequency f1 of the signal emitted by theship S1. Consequently the luminous spot will be deflected horizontallyby an amount f1.

In a similar manner the luminous spot of the cathode ray tube 2| will bedeiiected vertically by an amount representing [31 and horizontally byan amount representing f1.

Thus the coordinates a1, f1 of the luminous spot in the tube 20 togetherwith the coordinates 1, f1 in the tube 2| determine definitely theposition of the vessel S1 with respect to the station A and B.

In considering the operation of the device it should be remembered nowthat the motors I2 and I3 are in a continuous rotatory motion and causea continuous and periodic change in the tuning conditions of the aerialsI0 and II so that the latter become successively, and repeatedlyvexposed to the frequencies f1, fz, fn. To each of these frequenciescorresponds a determined spot in the tubes 20 and 2 I. By making thesuccession of the referred to frequencies sufficiently' rapid and byemploying on the screens of the cathode ray oscillographs a fluorescentmaterial, possessing an appreciable period of afterglow, the existenceof these spots can be made apparently or in reality simultaneous.

It is therefore apparent that I have provided a system for indicatingcontinuously on the tubes 20, 2| the position of the vessels S1, Sz, S3,Sn.

The arrangements so far described will give in the case of a ship, al1the information required. In the case of aircraft, a substantiallysimilar arrangement may be used in which the aerial arrays shouldpreferably be of the Adcock type which are substantially free fromaeroplane effect. Where there are employed closed coil aerials operatingon radiation from the aircraft which is substantially verticallypolarized, the projection of the position of the aircraft on the groundplane will be correctly represented, otherwise the position of theaircraft as represented will be subject to aeroplane effect.

Fig. 2 shows another embodiment of my inventionwhich consists inproducing records of the values a1, f1; a2, fz; an, fn; and of thevalues e1, f1; [32, f2; n, fn; separately and independently at thestations A and B respectively. This recording may be donephotographically and by comparing the records obtained at the station Awith those of the station B the presence of the enemy ships may bedetected and their positions determined.

Referring again to Fig. 2 there is represented an arrangement includedin the station A. It is understood however that the station B issubstantially similar to A. In this figure, 26, 21 designate thedirective antennae of the aerial I0, I6 and I1 are the respective tuningcondensers mounted on the shaft I4 and driven by the motor I2, 28 and 29are the amplifiers amplifying the respective outputs of the antennas 26,21 and 8|) designates an electronic divider producing a voltage whichrepresents the ratio of signals derived from the amplifiers 28 and 29respectively. l

The condensers I6 and I1 driven by the motor I2 are in a continuousrotation thus enabling the antennas 26, 21 to cover a predeterminedtuning range periodically in succession. In a manner which has beenexplained above the electronic voltage divider produces across itsoutput terminals the values a1, a2, a, periodically in succession. Thesevalues are subsequently transmitted to a moving coil galvanometer 8|which includes a coil 82 supported by suspension ber 83 and carrying amirror 84. 'Ihe coil 82 is adapted to swing in ay uniform field in theair gap between the pole pieces 85 and B8 of a permanent magnet. Thegalvanometer and its associated parts are housed in a recorder devicewhich is included in the dotted rectangle 81 in the gure. It is to beunderstood, of course that any suitable recording device may beemployed, one example, however being described so that my invention willbe more easily understood. A source of light 88 is adapted to focus apoint of light upon the mirror 84 which reflects the point of lightalong the path 89 to a photographic film 90 which is stretched in thepath of reflected beam. The lm is adapted to move in the direction ofthe arrow that is to be wound by the spool 9| which is driven by themotor I 2. A number of different forms of recording instruments may beused, as will be readily understood by those skilled in the art.

It will now be observed that the current delivered by the voltagedivider 80 and varying in intensity in accordance with the signals a1,az, an will pass through the coil 82 and will cause a deflection of thecoil and of the attached mirror, the magnitude of the said deflectionbeing proportional to instantaneous values of the current.

This is indicated by the beam of light, reected from the mirror on thefilm 90. At the same time the lm 90 moves in such manner that at anyinstant the position of the lm depends upon the angular displacement ofthe motor I2, which in turn determines the value of the condensers I6,I'I and consequently the frequency f.

It will be therefore apparent that the records obtained will besubstantially as shown in Fig. 3. Fig. 3 shows a strip of film obtainedby means of this arrangement. 'Ihe respective points along thelongitudinal axis of the film represent various frequencies f1, f2,fn,f1,f2 f1, fi and the corresponding transversal lines such as l1, Z2,ln, l1 ln, Z1 represent the bearings a1, a2, an, a1

A simila-r film is provided by the station B which gives the values i,,32, n and the corresponding frequencies i, f2, fn. By comparing thereferred to two films, the presence of the enemy vessels may be detectedand their positions determined.

It is therefore apparent that I have accomplished the objects of myinvention.

Consider now the electronic divider designated by blocks 34, 44 in Fig.1 and by block 80 in Fig. 2. Either of blocks, 34, 44, 80 represents atransducer provided with two pairs of input terminals and one pair ofoutput terminals and adapted to produce across the output terminals avoltage representing the ratio of the input terminals. In order tounderstand better my invention, I am including hereafter a diagram of anelectronic divider, shown in Fig. 4 and some explanatory remarksreferring to Fig. 4.

It is understood that my invention refers to an arrangementsubstantially as shown in Figs. 1 3, and that Fig.l4 refers only to oneof the elements of Fig. 1 and Fig. 2, and namely to the electronicdivider. The electronic divider contitutes the subject matter of U. S.Patent 2,129,880 granted to Serge A. Scherbatskoy and Jacob Neufeld onSeptember 13, 1938.

Briefly, in Fig. 4 numerals I |00., IIUb and I I I a, IIIb designate twopairs of input terminals and the numerals I30a, |3017 designate theoutput terminals of an electronic divider. As stated above, anelectronic divider is adapted to produce across its output terminals avoltage, representing substantially the ratio of voltages, appliedrespectively across the input terminals IIUa, IIUb and IIIa, IIIb.Theinput terminals IIOa, IIb are connected to a circuit consisting of aresistance II2 in series with a resistance II3. The input terminalsIIIa, IIIZ)` are connected to a circuit consisting of a resistance I I4in series with a circuit arrangement designated by a block II5,"the saidcircuit arrangement comprising two three electrode tubes I I 6 and II'Iconnected in pushpull, two resistors IIB, II9 connected across theanodes of the tubes IIS, II'I respectively, and a battery |20.insertedbetween the cathodes of: the tubes IIB, ||1 and the common terminal ofthe resistors I I8, II9 respectively. The terminal I2I of II isconnected directly to one of the terminals of I I 3 while the otherterminal of I I3 and the terminal |22 of II5 are respectively connectedto the input terminals |23, |24 of al D. C`. amplifier |25. The D. C.amplifier |25 is of a push-pull type well known in the art. One of theoutput terminals of the amplifier |25 is connetced to the cathodes ofthe tubes I I6, I I1 and the other output terminal of |25 is connectedthrough the battery |28 to the grids of the tubes II6, II'I.

The operation of this arrangement can be explained as follows:

Let R designate the resistance of II2 or II4, these two resistancesbeing equal one to another and let ri designate the resistance of II3.The electric circuit contained in the Iblock I I5 and inserted betweenthe terminals I2I, |22 acts primarily as a resistance; let the latter be'repre-1 sented by r2. It is apparent that the value of r2 depends amongother things upon the platecathode resistances of the tubes II6 andII'I. On the other hand, the plate cathode resistances of th'e tubes II6, II'I are functions of their grid biases, the latter being determinedby the voltage between the terminals I 30a, I3Ub.

Consequently the voltage between the terminals I3Ua, I30b can be usedfor controlling the equivalent resistance r2 of the block II5, and themagnitude of this voltage determines the value of the resistance r2.

The current flowing from the terminal IIIla into the resistor I I2 inseries with the resistor II3 and returning to the terminal IIUb can beexpressed as follows:

li-gl (l) Assuming that ri R the expression (l) reduces to and thevoltage across the termina-ls of the resistance II3 can be expressed asfollows:

In a similar manner, the currentvowing from the terminal I I Ia into theresistor. I I4 and traversng the block II5 from the terminal |22 to theterminal I2| and entering into the terminal IIIb can be expressedl asfollows:

Assuming that rz R the expression (4) reduces to and the voltage acrossthe terminals |22 and |2| becomes 112.2'5272 Elia/i2 (6) The voltages v1and 'U2 `oppose each other in such a marmer that the voltage v3 acrossthe input terminals |23, |24 of the D. C. amplier |25 is equal to thedifference of v1 yand tz, i. e.,

and the amplied voltage across the output ter#- minals |30a, |30b of theD. C. amplifier is U4=KU3 E11'1- E2`72] Where K is an amplificationfactor.

The voltage v4 in series with the voltage of the battery |28 constitutesthe grid bias of the tubes H6, Ill. It is apparent that v4 determinesthe plate resistance of the tubes and also determines the resistance r2of the block I5. Under the conditions shown in the figure the value ofrz is such as to render the expression very small, i. e.,

and

E ar-tif Assume that the expression (9) is zero, i. e.,

garrafa@ 10) whence Let r1 be equal to one ohm. Then It is thus seenfrom the formula (12) that the magnitude of the resistance r2numerically expresses the ratio of the voltages E1 and E2. C'onsequentlythe problem of determining the ratio of voltages across the terminalslla, H017 and Illa, |||b is equivalent to determining r2, i. e., theequivalent resistance of the block H between the terminals |2| and |22.On the other hand the value of r2 is controlled and determined by thevoltage v4 across the output terminals |300., |3017. Consequently in theexpression (12) instead of measuring the value r2 expressing the ratioE1/E2 it is suicient to determine the voltage v4 which corresponds tothe given value of r2, the said voltage v4 being measured across theoutput terminals |300., |30b.

If now the relative values of the voltages El and E2 change, the voltageacross the output terminals |30a, |301) will indicate a new value of the-ratio Ei/Ez and, in general, in case of varying Assume forv instancethat the voltage E2 increases and the voltage E1 is maintained constant.Then the current iz and the voltage v2 will also increase, and willcause a corresponding variation of the voltage v3. 'I'hen the ampliedvoltage v4 derived from the output terminals of |25 changes its value insuch a manner as to cause a decrease of the resistance rz of the block II5. Then the voltage drop o2 across the resistor r2 becomes againsubstantially equal to the voltage drop 'v1 across the resistor r1 sothat the relation is substantially satisiied. It should be noted,however, that in this case the resistance r2 has a different and asmaller value which corresponds to a new and a smaller value of theEi/Ez. To this new value of r2 corresponds the new value of v4 which isdirectly indicated by the voltage across the output terminals |30a,|3012.

It is therefore apparent that the electrical circuit, substantially asshown and described in connection with Fig. 4 operates as an electronicdi'- vider and may be substituted in place of blocks 34, 44 in Fig. 1and in place of block 80 in Fig. 2.

In View of my invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain part or all of the benefits of myinvention without copying the structure shown, and I, therefore claimall such in so far as they fall within the reasonable spirit and scopeof my invention:

I claim:

1. Method of determining directions of stations radiatingelectromagnetic waves which includesv receiving the said waves,producing signals representing directions of the said waves, producingsignals the magnitudes of which represent individually frequencies ofthe said waves, and producing a compound indication of the saiddirection representing and the said frequency representing signals.

2. In an apparatus for determining direction of radio waves a directionnder for producing signals indicating directions of radio waves whentuned to the frequency of the said waves, a light source projecting abeam of light upon a light sensitive element, a single means for movingthe light sensitive element and for simultaneously varying the tuning ofthe direction finder, means responsive to the said signals forcontrolling the beam of light in order to produce upon the lightsensitive element spots representing directions of the said transmittingstations.

3. An apparatus for {determining angles of incidence of radiant energyemanating from a plurality of mobile sources of radiations, the saidsources being located on ships, planes or the like, comprising twoantennas, at least one of the said antennas having directionalcharacteristics, means for changing continuously the tuning of the saidantennas in a manner as to cover a predetermined frequency range Withinwhich the said radiation sources are located and for repeatingperiodically in succession the said tuning conditions thus receivingsuccessively and repeatedly the signals emanating from the said sources,means responsive to signals received by the said two antennas forproducing a signal representing substantially ratios of the magnitudesof the signals received by the said two antennas, means for producingsignals identifying the said sources and means for indicating the said4. An arrangement for recording directions of radio waves comprising adirectional antenna for receiving the said waves and producing signalsrepresenting directional components of the said Waves at the point ofreception, means responsive to the said components for producingindications representing directions of the said waves, means forproducing indications identifying the said Waves and means for combiningthe said indications'in form of a diagram.

5. An arrangement for recordng Adirections of radio waves comprising adirectional antenna for receiving the said Waves and producing signalsrepresenting directional components of the said Waves at the point ofreception, means responsive to the said components for producingindications representing directions of the said Waves, means forproducing .indications representing frequencies of the said Waves andmeans for combining the said indications in form of a diagram.

6.'In a method of determining directions of radio waves having differentfrequencies, the step of producing. a beam of light, the step ofsuccessively receiving said Waves at time intervals characteristic ofthe frequency spacing between the said waves, and the step of deectingthe said beam in response to the said waves by an amount related to thedirections of thesaid Waves.

7. In a method of recording on a limited portion of a surface directionsof radio Waves having different frequencies, the step of producing abeam of light, the step of receiving said Waves and the step of deectingthe said beam in response to the said Waves by anamount related to thedirections of the said Waves and the step of recording the saiddeflections at determined positions on the said surface, the saidpositions representing frequencies of the said Waves.

8. 'In a method of recording on a limited p0rtion of a surfacedirections of radio waves having different frequencies, the step ofproducing a beam of light, the step of successively receiving said Wavesat time intervals characteristic of the frequency spacing between thesaid waves, the step of deflecting the said beam in response to theVsaid waves by an amount related to the directions of the said waves,and the step of recording the said deections at determined positions onthe said surface, the said positions representing frequencies of thesaid waves.

9. In a, method of determining directions of radio transmitting Waveshaving diiferent frequencies the step of receiving the said waves attime intervals characteristic of the frequency spacing between the saidwaves, the step of producing a beam of light, the step of deflecting thesaid beam of light in response to the reception of the said Waves to theamount related to the said directions and the step of repeatingcontinually and periodically the said deflecting.

10. In a system for recording directions of incoming waves, the saidWaves having dierent frequencies, a receiving station for continuallyand repeatedly receiving said waves and for producing continually andrepeatedly signals representing directions of the said waves, a lightsensitive element, a light source projecting a beam l.

of light upon the light sensitive element, means responsive to the saidsignals for controlling the said beam of light in order to produce onthe light sensitive element spots representing directions of the saidWaves, and means for spacing the said spots on the light sensitiveelement at intervals characteristic of frequency spacing between thesaid waves.

11. In an arrangement for recording directions from which radio signalsare received a radio receiving station having directional receivingapparatus and producing indications of directions from Which radiosignals are received, the said station comprising a tuning elem-ent, arecorder responsive to the said indications for recording andidentifying the said directions, a single means for varying said tuningelement and for simultaneously operating the said recorder. c

12. In an arrangement for recording directions from which radio Wavesare received, means for receiving said waves and for producing signals,the magnitude of each of the said signals representing individually thedirection of a corresponding Wave, the said means comprising a tuningelement, means for varying said tuning element, a recorder operated in adefinite time relation to the said varying means and responsive to thesaid signals for recording and identifying the said directions.

13. In a system for recording directions of incoming waves havingdiierent frequencies, a receiving station for receiving the said Wavesat time intervals characteristic of the frequency spacing between thesaid waves, a light sensitive element, a light source projecting a beamof light upon the light sensitive element, means responsive to theoutput of the said receiving station for deecting the said beam by anamount related to the directions of the said waves.

14. In a system for recording directions of incoming waves havingdifferent frequencies, a light sensitive element, a light sourceprojecting a beam of light upon the light sensitive element, means forcontinually and repeatedly receiving the said waves at time intervalscharacteristic of the frequency spacing between the said waves and forcontinually and repeatedly deflecting the said beam by an amount relatedto the directions of the said Waves.

JACOB NEUFELD.

